Initial System Integrity Assessment for Safety: Methods and NGOps-4 Results

摘要

This paper describes a novel method for assessing the safety-related integrity of complex systems and associated cost risk during concept development. This Initial System Integrity Assessment (ISIA) and cost estimation process assesses program susceptibility to prescribed vulnerabilities, identifies mitigations for them, and costs those mitigations, providing a cost risk estimate for the programs, based on the initial vulnerability assessment. The methodology was developed concurrently with its application to the implementable architecture defined by the Joint Planning and Development Office as NextGen Operational level four. NGOps-4 is a future (beyond 2025) complex system concept intended to increase significantly the capacity of the air transportation system. Performance improvements supporting increased capacity often increase the levels of safety criticality that must be accounted for in business case analyses for NextGen architectures, like NGOps-4. Subject matter experts qualitatively identify and assess the vulnerabilities and identify cost categories affected by mitigations. These two inputs drive valuable program and portfolio management artifacts at each stage of the ISIA process, including experiential vulnerabilities, justified susceptibility assessments, recommended mitigations, mitigation cost factors, and program cost risk early in a program's lifecycle. ISIA artifacts can serve as inputs to later lifecycle program and portfolio assessments and act as the basis for ensuring risk retirement or mitigation. This initial ISIA application considered safety-related cost risk; however, the ISIA process can determine other program performance metrics such as schedule risk.